The production and consumption of thorium
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ABSTRACTS OF FUTURE PAPERS Atomnaya Energiya Vol. 5, No. 2 (1958)
Effect of neutron temperature on the duration of runs and on fuel breeding in a power reactor: A. K. Krasin, M. E. Minashin and V. J. Sviridenko.
Calculations on the effect of neutron gas temperature on the working time, a3aPu yield and electrical power produced are given. The calculations mainly relate to two forms of core in a uranium-graphite reactor, sodium-cooled; the fuel cans are of Zr (type I) and steel (type 2). A gas temperature of 900- 1OOOK is shown to be economically the best. The calculations on fuel breeding and working time between fuel changes have also been extended to homogeneous sodium-graphite and heterogeneous gas-cooled uranium-graphite reactors. The results are given as graphs. The production and consumption of thorium: G. E. Kaplan, Yu. I. Zarembo and T. A. Uspenskaya.
The developing use of Th in nuclear energy and in producing high-melting Mg alloys has caused thorium production to expand rapidly, and has stimulated research on thorium. Several undertakings concerned with extracting Th from its ores have been set up in the USA, India, Brazil, etc. Alkali methods are mostly used to extract Th and rare-earth elements from monozite. Extraction processes are commonly used to give pure Th compounds. Metallic Th is produced by using other metals, or by electrolysis in fluoride baths, with or without chloride. Compacted Th metal is produced by sintering or fusion. Metallic thorium: G. A. Meerson and A. F. Islankina.
The metallurgy of Th is briefly reviewed. Soviet studies on producing solid Th metal by powder methods are given. The physicochemical and technological characteristics of Th powder produced by electrolysis or by the calcium process are given. The calcium-derived powder presses worse than the electrolytic because more oxide films are present. The main aspects of sintering are considered theoretically, and relationships for the strength and plasticity as functions of sintering temperature and time are given for both types of Th powder. Briquettes made from the Ca-derived powder, without open pores, distort badly on sintering above 11561200C because Ca evaporates. A secondary or correction pressing followed by annealing is required to give a compacted metal. The physical and mechanical properties of Th metal produced from the two powders are given; the electrolytic powder gives the more plastic metal (d = 35-43 %) which is weaker (U.T.S. = 16.5 kg/mm2); the Ca powder has 8 = 17-23 % and U.T.S. = 22 kg/mm2. Heats of formation of UAI,, UAl, and UAI,: M. I. Ivanov, V. A. Tumbakov and N. S. Podolskaya.
UAl,, UAI, and UAI, were produced by diffusion on heating Al and U powders; the U powder was prepared by decomposing the hydride and powdering the product, followed by re-heating. All operations were done in purified argon at room temperature. X-ray studies (Debye camera) showed that the prepara- tions consisted of a single phase each; the structure parameters are close to published figures. Analysis in terms of hydrogen evolved on dissolution in a special solvent (a mixture of HCl, HaPO,, Na,SiF,, H,PtCl, and CuSO,.SH,O) showed that the preparations had the expirical formulae UAI,.,,,, UAl,.,,, and UAI,.,,,. The differences between the heats of solution of the aluminides and the components gave the - AHO,,s values (corrected for composition).as 22.3 + 2.4, 25.2 f 2.2 and 31.2 + 3.1 kcal/mole respectively. Heating of the structures round a nuclear reactor: A. N. Komarovskii.
The effects of heating and radiation from a reactor on a concrete biological shield are considered; the various types of concrete used for the purpose are considered. Test data are given on the mechanical parameters and moisture contents of concrete shields from functioning reactors. Data are also given on heat screening materials and methods of cooling the biological shield. The mass dlstrihution of fragments resulting from the fission of zssU, zsaU and zs*Pu induced by 14.6 MeV neutrons: A. N. Protopopov, G. M. Tolmachev, V. N. Ushatskii, R. V. Venediktova, I. T. Krisuk, L. P. Rodionova and G. V. Jakovleva.
Our knowledge of fission processes is extended by studies on fission fragment mass distributions; data on the relative fragment yields are also required in various practical radioisotope applications. The methods used and results from measurements of the yields of certain fragments from essU, aasU and sasPu produced by 14.6 MeV neutrons are given. Curves are drawn through the experimental and reflected points for the yields of the masses. Certain features of the distributions are discussed. A multichannel time-of-flight fast neutron spectrometer: A. A. Kurashov, A. F. Linev, B. V. Rybakov and V. A. Sidorov.
A multichannel time-of-flight fast neutron spectrometer is described which uses the natural modulation of a cyclotron beam. The time analyzer works on the vernier principle, the channel widths being about 1 rnp sec. The recording system has 256 channels, each of capacity 2i8 pulses. Production of we&&able amounts of OsTc by neutron irradiation of molybdenum: Vict. I. Spitsyn and A. F. Kuzina. -
Various methods of separating Tc from thermal neutron irradiated molybdenum oxide are considered. A method based on coprecipitation with sparingly-soluble phosphates and chromatographic purification has been developed and tested; mg amounts of s8Tc have been produced. The Tc has been identified by soectral analvsis: the absolute activity and maximum j?-ray energy have been determined. Certain chemical properties oiTc.have been studied. _ The accumulation of radioelement in certain groups of water organisms: D. I. Ilin, Yu. I. Moskalev and A. I. Petrova.
The radioisotope contents are studied of certain species of organisms introduced into an experimental water tank with water of specific activity 24 x IO-* curies/litre. The plankton, benfos and fish selectively concentrated sap *sSr, Wr, isrCs and *4Na; and isrCs the values were lOs-lo*.
for s*P the excess concentration was lOs-104, while for se. OSr, The B-active isotopes in the fish were mainly concentrated in the muscles
(44-59 %) and skeleton (16-24 %). The B- emitter concentrations in skeleton, gills, fins and skin were 3-5 times greater than in the soft tissues.